(±)-3a,6,6,9a-tetramethyldodecahydronaphtho[2.1-b]furan (hereinafter, referred to as (±)-Ambroxan) is a material of an amber-like fragrance having an excellent aroma property and fragrance retention, and thus it is used as a raw material of a fragrance composition and for perfuming to various products.

Several methods for producing (±)-Ambroxan are known. Recently, methods for producing (±)-Ambroxan through N,N-dialkylhomofarnesic acid amide have been reported. For example, Patent documents 1, 2 and Non-patent document 1 disclose methods for producing (±)-Ambroxan from nerolidol as a starting material through N,N-dimethylhomofarnesic acid amide. As a method for obtaining the N,N-dimethylhomofarnesic acid amide, a method of reacting the nerolidol with N,N-dimethylformamide dimethyl acetal is disclosed.
